Hi ItsmeJPaulC,
If your physiotherapist is specialised in sports, then you can probably trust him. Return to sport is possible if you train up your agility, strength and endurance gradually. You may not be 100%, but maybe close depends on your condition. However, you are still more at risk now than you were before the injury. Your knee will also degenerate quicker compare to your other leg, because of your past injury. How serious do you play football? like professionally? or just causal? Because when playing sports, things happen very quickly and sometime you just dont have the time to prepare yourself for actions like sudden stop, sudden turning. These can be dangerous for the knee. Also there are external factors like someone kicking on your lower leg while you are standing on that leg. That would be dangerous too (i know nothing about Gaelic Football). So if the matches are quite competitive I would not want expose myself to those kind of risks again. You can call me chicken, I just like to be on the safe side all the time. I even tell my friends to avoid running, hiking or unnecessary stairs to minimize the risk of knee degeneration. I am kinda extreme on that, I have seen plenty of people has their mobility very limited by their knees, and I already have knee pain from work.
Talk to your physiotherapist again and decide if you want to take those risks, then you have your answer.